2 Epression data analysis

Author

Izar de Villasante

3 Loading data:

3.1 Sample sheet

3.2 Expression:

3.2.1 Counnts:

namedlist <- function(...) {
  nl <- list(...)
  argnames <- sys.call()
  n<-sapply(argnames[-1], as.character)
  names(nl)<-n

  
  return(nl)
  }

library(readxl)
library(data.table)
counts<-list()
Tat72_off <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/Tat72VSTetOFF.xlsx", sheet = 1)

New names:
• `` -> `...1`

colnames(Tat72_off) <- c("gene",sapply(colnames(Tat72_off),function(x)unlist(strsplit(x,"\\."))[7])[-1])
setDT(Tat72_off)
Tat72_off[,ID :=tstrsplit(gene,"\\.",keep=1)]

Tat_Tat72 <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/TatVSTat72.xlsx", sheet = 1)

New names:
• `` -> `...1`

colnames(Tat_Tat72) <- c("gene",sapply(colnames(Tat_Tat72),function(x)unlist(strsplit(x,"\\."))[7])[-1])
setDT(Tat_Tat72)
Tat_Tat72[,ID :=tstrsplit(gene,"\\.",keep=1)]


Tat_off <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/TatVSTetOFF.xlsx", sheet = 1)

New names:
• `` -> `...1`

colnames(Tat_off) <- c("gene",sapply(colnames(Tat_off),function(x)unlist(strsplit(basename(x),"\\."))[1])[-1])
setDT(Tat_off)
Tat_off[,ID :=tstrsplit(gene,"\\.",keep=1)]

counts <-namedlist(Tat72_off,Tat_Tat72,Tat_off)

dtable(counts[[1]])

Warning in instance$preRenderHook(instance): It seems your data is too big for
client-side DataTables. You may consider server-side processing:
https://rstudio.github.io/DT/server.html

3.3 DEGs:

library(readxl)
library(data.table)

Tat72_off <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/Tat72VSTetOFF.xlsx", sheet = 3)
Tat72_off$Contrast="Tat72_off"
Tat_Tat72 <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/TatVSTat72.xlsx", sheet = 3)
Tat_Tat72$Contrast="Tat_Tat72"
Tat_off <- readxl::read_xlsx("data-raw/Transcriptome_HClinic_Vcasanova_20042023/TatVSTetOFF.xlsx", sheet = 3)
Tat_off$Contrast="Tat_off"

dt_DEGs <- data.table::data.table(rbind(Tat_Tat72,Tat72_off,Tat_off))
# dt_DEGs <- dt_DEGs[RealFC<0.5 | RealFC >2,]

dtable(dt_DEGs)

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client-side DataTables. You may consider server-side processing:
https://rstudio.github.io/DT/server.html

3.4 Methylation:

“El primer objetivo es ver si la proteína TAT del VIH, induce cambios en el metiloma. La proteína TAT está codificada por 2 exones que realizan funciones diferentes y queremos además aislar el efecto de cada uno, por eso hemos generado unas líneas celulares de jurkat establemente transfectadas con:

Un vector vacío que será nuestro control: muestras 1, 7 y 13 (triplicados)
Un vector con la proteína TAT completa: muestras 3, 9 y 14 (triplicados)
Un vector con solo el primer exón de TAT: muestras 5, 11 y 16 (triplicados)

La comparativa entre estos tres grupos es la primera que nos interesa. a-b, a-c y b-c.”

Por otro lado, la DOXYCICLINA “apaga” la expresión de TAT y el segundo objetivo entonces es ver si el “apagado” de TAT con la DOXY hace algún cambio en el metiloma. Por eso la comparativa aquí sería cada una de las tres líneas anteriores con y sin DOXY, así que tendremos además las siguientes muestras:

Un vector vacío que será nuestro control + DOXY: muestras 2 y 8 (duplicados)
Un vector con con la proteína TAT completa + DOXY: muestras 4, 10 y 15 (triplicados)
Un vector con solo el primer exón de TAT + DOXY: muestras 6 y 12 (duplicados)

La segunda comparativa que nos interesa, por tanto, es. a-d, b-e y c-f.

While the first objective yielded positive results no difference was found for the second (Doxi) apporach.

3.4.1 Overview:

PCR plots:

3.4.2 DMRS:

dmrs<-readRDS("data/dmrs.rds")
ano_cols<-c("seqnames","start","end","width","no.cpgs","HMFDR","meandiff","Contrast")
dt_list<- lapply(
  1:NROW(dmrs),function(rn){  # For every position or ProbeID do:     
    UCSC <- data.table(      # 1. generate a data.table (per row)
      dmrs[rn,       # 2. split UCSC gene and position    
               lapply(       # 3. new row for every combination of gene/position
                 overlapping.genes,        # 4. add Contrast porbeID and bval difference
                 function(x)unlist(strsplit(x,","))
                 )
               ,by=ano_cols]
      )
    })
dt_dmrs <- rbindlist(dt_list)
DMRs <- dt_dmrs[,Gene:=V1][!is.na(V1),]
DMRs$V1 <- NULL
# c1<-DMRs[Contrast== "Control_No-Exon1_No",.(.SD,meandiff=-meandiff,Contrast="Tat72_off"),.SDcols=ano_cols[!ano_cols %in% c("meandiff","Contrast")]]
c1<-DMRs[Contrast== "Control_No-Exon1_No",]
c1$Contrast <- "Tat72_off"
c1$meandiff <- -c1$meandiff

c2<-DMRs[Contrast== "Control_No-TAT_No",]
c2$Contrast <- "Tat_off"
c2$meandiff <- -c2$meandiff

c3<-DMRs[Contrast== "Exon1_No-TAT_No",]
c3$Contrast <- "Tat_Tat72"
c3$meandiff <- -c3$meandiff
DMRs<-rbind(c1,c2,c3)
saveRDS(DMRs,"data/DMRs.rds")

dtable(DMRs)

4 Correlation:

4.1 DMRs vs expression

dt_DEG_DMR <- merge(DMRs,dt_DEGs,by=c("Gene","Contrast"),all = T)
tab <- dt_DEG_DMR[,.(DEGs=sum(!is.na(ID)),DMRs=sum(!is.na(start)),overlap=sum(!(is.na(start)) &!(is.na(ID)) )),by=c("Contrast")]
kableExtra::kbl(tab)|>kableExtra::kable_classic_2()

Contrast	DEGs	DMRs	overlap
Tat_Tat72	3087	1092	224
Tat_off	3102	990	207
Tat72_off	1594	53	8

4.1.1 Venn diagrams:

4.1.2 DEG/DMR overlapping Correlations:

Now we want to get the mean beta value for each sample in the dmr location: 1. Find all cpg that fall in the dmr 2. get the mean for each sample 3. Match each sample bVal with it’s expression value. (No way to do it, since there is no key sample to sample) 4. Make correlation 5. Plot.

ol <- dt_DEG_DMR[!(is.na(start)) &!(is.na(ID)),]

library(data.table)
library(GenomicRanges)
library(IlluminaHumanMethylationEPICanno.ilm10b2.hg19)

locs <- IlluminaHumanMethylationEPICanno.ilm10b2.hg19::Locations
locs.ranges <- GRanges(locs$chr, IRanges(locs$pos, locs$pos))
names(locs.ranges) <- rownames(locs)

dt_DEG_DMR_intersect<-lapply(1:NROW(ol),function(nr){
  cont<-ol[nr,Contrast]
  xpr <- counts[[cont]][ID==ol[nr,ID]]
  xpr<-xpr[,.SD,.SDcols=names(xpr)[!(names(xpr)%in%c("ID","gene"))]]
  expression <- suppressWarnings(melt(xpr,measure.vars=colnames(xpr),variable.name = "SID",value.name = "TPM" ))
  SIDs <- as.character(expression$SID)
  cgs <- names(subsetByOverlaps(locs.ranges,GRanges(ol[nr,])))
  
  b<-betas[probeID %in% cgs ,lapply(.SD,function(x)mean(x,na.rm=T)),.SDcols=SIDs] 
  meth <- suppressWarnings( melt(b,measure.vars=colnames(b),variable.name = "SID",value.name = "DMR.meth" ))
  # list(meth,expression)
  m <- merge(meth,expression,by="SID")
  m <- m[,lapply(.SD,as.numeric),by=SID]
  dt<-cbind(ol[nr,],m)
  cor<-cor.test(dt$DMR.meth,dt$TPM)
  dt$correlation <- cor$estimate
  dt$cor.pval <- cor$p.value
  return(dt)
  })|>rbindlist()
dt_DEG_DMR_intersect[,grp:=tstrsplit(SID,"_",keep = 1)]

dt_cor <-dt_DEG_DMR_intersect
setorder(dt_cor,cor.pval,Gene)
saveRDS(dt_cor,"data/dt_cor.rds")

4.1.2.1 Table for DMR & DEG:

In the following table the values for methylation and expression are integrated:

dtable(dt_cor[,.SD,.SDcols=c("Gene","Contrast","SID","DMR.meth","TPM","correlation","cor.pval")])

4.1.3 Plots

library(ggplot2)
library(data.table)
library(ggpubr)
library(ggrepel)
DMR_DEG_plots <- list()
plots_folder <- "analysis/Integration_with_expression/DEGvsDMR/pval"
dir.create(plots_folder,recursive = T,showWarnings = F)
setkeyv(dt_cor,c("cor.pval","Gene","width"))

for(cont in unique(dt_cor$Contrast)){
  dt<-head(dt_cor[Contrast==cont,],60)
  lg <- dt[,.(gene=unique(Gene),width=unique(width)),by=cor.pval] 
  
  plist <- lapply(1:NROW(lg),function(nr){
    pdata <- dt_cor[lg[nr,]]
    plot_name <- paste0("/DEG_DMR.pval_", nr, ".png")
    plt_path <- paste(plots_folder, cont, sep = .Platform$file.sep) 
    dir.create(plt_path,recursive = T,showWarnings = F)
    p<-ggplot(data=pdata, aes(x=as.numeric(TPM),y=as.numeric(DMR.meth),colour=SID)) +
    geom_point(aes(shape=grp),size=8,alpha=0.6) +
    xlab("Mean DMR methylation") + ylab("Transcripts x Milion") +

    geom_smooth(method = "lm",
                inherit.aes = F,
                aes(x=as.numeric(pdata$TPM),y=as.numeric(pdata$DMR.meth)),
                linetype="dashed",
                se=F)+
    
    annotate(geom = "text",
             x = -Inf, y = Inf,
             label=paste0("correlation: ", round(unique(pdata$correlation),4), ", p-value: ", round(unique(pdata$cor.pval),8)),
             hjust = 0, vjust = 1
             )  +

    ggtitle(paste0(" Correlation between expression and methylation for gene: ",unique(pdata$Gene)))
    ggsave(path = plt_path, filename = plot_name, plot=p)
    return(p)
  })
  DMR_DEG_plots[[cont]] <- plist
  }
saveRDS(DMR_DEG_plots,"data/DMR_DEG_plots.rds")